Promethazine 25 mg Tablet: What It Treats, How to Use, and Side Effects

Promethazine 25 mg: Complete Guide to Uses, Dosage & Side Effects

What is Promethazine 25 mg?

Promethazine 25 mg is a first-generation antihistamine used to treat allergies, motion sickness, nausea, and vomiting. It also serves as a sedative and preoperative medication. Promethazine works by blocking histamine (H1) receptors in the brain and other parts of the body, and has antiemetic, anticholinergic, and sedative properties.

📋 Indications / Uses:

Promethazine 25 mg is prescribed for:

• Allergic conditions: hay fever, urticaria (hives), rhinitis, and skin rashes
• Motion sickness: prevention and treatment of nausea and vomiting
• Nausea & vomiting: from various causes, including postoperative and drug-induced
• Sedation: preoperative sedation and nighttime sleep aid
• Cough and cold symptoms (as part of combination therapies)
• Anxiety-related nausea (off-label use)

⚠️ Not recommended in children under 2 years due to risk of severe respiratory depression

💡 How It Works:

Promethazine:

• Blocks histamine H1 receptors, reducing allergy symptoms
• Acts on the medullary chemoreceptor trigger zone (CTZ) to reduce nausea and vomiting
• Possesses central nervous system (CNS) depressant effects, which contribute to its sedative and antiemetic actions

💊 Dosage & Administration:

💬 Always follow the exact dosage prescribed by your doctor.

📌 Typical Dosages:

• Allergic reactions: 25 mg at bedtime or 12.5 mg 2–3 times daily
• Motion sickness: 25 mg taken 30–60 minutes before travel; then every 12 hours if needed
• Nausea/vomiting: 12.5–25 mg every 4–6 hours as needed
• Sedation (preoperative or nighttime): 25–50 mg at bedtime
• Elderly patients: Lower doses recommended due to higher sensitivity to side effects

🕒 How to take:

• Oral tablets should be swallowed whole with water
• Best taken with food or milk to minimize stomach upset
• Do not exceed prescribed dosage — especially important for children and older adults

⚠️ Precautions & Warnings:

• May cause drowsiness or dizziness — avoid driving or operating machinery
• Avoid alcohol — it intensifies CNS depressant effects
• Use with caution in patients with:
  • Glaucoma
  • Asthma or other lung conditions
  • Enlarged prostate
  • Heart disease
  • Liver problems
• Can cause photosensitivity — avoid excessive sun exposure

🚫 Contraindications:

Do not use Promethazine 25 mg if you have:

• Hypersensitivity to promethazine or other phenothiazines
• Severe CNS depression or coma
• Children under 2 years old (due to respiratory depression risk)
• Concurrent use with other strong CNS depressants unless monitored

🔄 Drug Interactions:

Promethazine may interact with:

• CNS depressants (e.g., opioids, benzodiazepines, alcohol)
• MAO inhibitors (can intensify effects and risks)
• Anticholinergics (increase risk of side effects like dry mouth, constipation)
• Certain antipsychotic medications

⚠️ Side Effects:

✅ Common:

• Drowsiness
• Dizziness
• Dry mouth
• Blurred vision
• Constipation
• Headache

❗ Serious (seek medical help):

• Respiratory depression
• Seizures
• Irregular heartbeat
• Confusion or hallucinations
• Severe allergic reaction (rash, itching, swelling)
• Jaundice (yellowing of the skin or eyes)

Children and older adults are more prone to side effects like agitation or confusion.

🤰 Use in Pregnancy and Breastfeeding:

• Pregnancy: Category C — may be used if clearly needed (commonly used for nausea during pregnancy)
• Breastfeeding: Use with caution; may pass into breast milk and cause sedation in infants

👶 Use in Children:

• Under 2 years: Contraindicated due to fatal respiratory depression risk
• Over 2 years: Use with caution; dosage must be carefully adjusted

🧪 Monitoring:

• Monitor for excessive sedation or allergic reactions
• For long-term use: periodic liver function and blood tests may be advised

📦 Storage:

• Store at 20–25°C (68–77°F)
• Protect from light and moisture
• Keep out of reach of children

📈 Effectiveness:

• Fast-acting relief of nausea, allergies, and motion sickness
• Long duration of action (4–6 hours or more)
• Particularly useful as part of pre-surgery sedation or combination cold/flu therapy